High-frequency electron tube and circuit



Patented Apr. 27, 195 4 UNITED srA-rss PATENT oF-FicE s HIGH-FREQUENbZ ZI L ZJTRON TUBE AND Paul Haas, New

Sylvania Electric of'Massachus'etts Hyde Park, N. Y., assignor to Products 'Inc., a corporation Application March 13, 1948, Serial No. 14,726

1 Claim.

This invention relatesv to electron-discharge tubes and, more generally, to electron-discharge tubes combined .in high-frequency circuits.

Bypass structuresare often required for maintaininga pair of electrodes connected in a highfrequency circuit at different direct-current potentials without however interrupting'the highfrequency circuit. Tubes .of the so-calledplanargrid type are often usedin high-frequency circuits in which the annular terminal of one electrode-is connected to one Wall of a bypass structure that surrounds the terminal. Tubes and tube-circuit combinations of this kind are subjected to severe impact in special applications.

An object of thepresent-invention is toirnprove bypass constructions. used. in: combination with electron-discharge .tubesof the planar-grid type, for making thecombination simpler, more effective, and easier to assemble.

A further object. is to improve electron-discharge devices in respect to their ability to withstand extreme impact stresses.

According to one phase of this invention, the envelope of a planar grid tube is formed in part of a hollow metallic extension of the planar grid terminal. This terminal can be connected in the high-frequency circuit, and in this combination the extension can be utilized as one wall of a bypass structure. That terminal and extension also act as a function to resist acute endwise acceleration stresses applied by a non-metallic wall or envelope-portion that carries another electrode. As a further feature the metal portion of the envelope is tapered, somewhat as a cone, for firm seating of the envelope for imparting excellent shock resistance to the tube-and-circuit combination. Furthermore, by properly proportioning the metal envelope wall, the bypass can be made to assume the dimensions necessary to serve also as one wall of a coaxial quarter-wave line having an open termination. In the circuit assembly, this results in injecting a minimum of impedance where the triode joins the high-frequency circuit. This is a feature disclosed but not claimed in copending application Serial No. 14,80 filed March 13, 1948, by George D. O'Neill.

Further objects and features of novelty will be apparent from the following detailed description of an illustrative embodiment of the several features of this invention, from which the foregoing objects and features of novelty will be more fully understood and appreciated. The single figure in the accompanying drawing is a longitudinal cross-sectional view of an illustrative tube and high-frequency circuit combination.

in its circuit assembly and In the drawing, circuit assembly Ill-includes multiple components threaded together to enclose and firmly support a triode l2. This circuit and tube combination, used iorillustrative purposes, forms a dynatron oscillator 'more'fully described in copending application Serial No. 681,454, filed July 5, 1946, by George D. ONeill. In this dynatron oscillator a high-frequencyoscillation is set up between positive grid' Hland dynode or secondary-emitting anodedfipwhich oscillation is utilized to excite resonator H! for yielding energy to load coupling device'2ll. The triode also includes acathode 22 for supplying the electron stream for grid l4 and dynode 48. A pair of leads are providedfor'heating'the-filamentary cathode, only one 24 of whichis shown, and a third lead 26 for flashing the'gettenand for direct-current connection to the positive grid. Dynode I6 is carried by a rod 28 which is sealed in a glass portion 30 forming a wall of the triode envelope that insulates dynode IB and positive grid l4 apart. Glass wall 30 is enclosed-in the high-frequency field set up in cavity IS without adverse effect. Planar grid I4 is supported in a threaded ring 32 and is thus adjustably carried by annular terminal 34 of the planar grid to which glass wall 30 is sealed hermetically. For coupling positive grid [4 into the high-frequency circuit including resonator IS, without short-circuiting the positive grid to the dynode in respect to direct current, a bypass construction generally designated 36 is provided including an insulating sleeve 38. Ring 32, annular terminal 34 and rod 28 are inactive in respect to the generation of the oscillations, but they constitute active portions of the high-frequency circuit and in effect constitute parts of a coaxial resonator including cavity IS. The bypass surrounds terminal 34 at the point where that terminal is to join the remainder of resonator 18, so that only a loop or edge portion 58 of the bypass divides the external resonator I8 and annular terminal 34.

Bypass 36 here assumes the form of a quarterwave concentric or coaxial transmission line having an open termination. Sleeve 40 forming a structural part of resonator 18 serves as one wall of the bypass 36. The other wall 42 of the bypass is also the lower side-wall of the evacuated envelope. Walls 40 and 42 of the bypass are extended to open termination 44 of the open quarterwave transmission line by the upper end of composite tube 50, 52, 54 and by bottom metal wall 48 of the triode, and dielectric sleeve 38 is extended by dielectric ring 46. Metal envelope portions 48 and 42 are welded together at their edges to form a flange 56 that is clamped within dielectric members 38 and 48 when tube 50 is tightened into sleeve 40. The external diameter of envelope portion 42 and the internal diameter of sleeve 40 decrease with increasing distance from tube 50, so that when tube 50 is tightened into sleeve 43 the metal envelope becomes firmly clamped and seated. Dielectric sleeve 38 is of sufiiciently yielding nature to accommodate slight irregularities either in envelope portion 42 or sleeve 40, and slight eccentricities of the envelope and the sleeve.

The impedance of open-termination 44 desirably is infinite, so as to be transformed at the input gap 58 to zero impedance. However there is the possibility of coupling between resonator I8 and the exterior at the open-termination 44, and to decrease this coupling (which may cause losses and instability) a series-connected pair of short-circuited lines 60 and 62 is arranged in seriesv with gap 44. The result is to produce very nearly ideal zero-impedance conditions at gap 58. Cavities, or more properly coaxial lines 60 and 62 are provided by properly shaping the nested tubes 50, 52 and 54. This features is disclosed and claimed in copending application Serial No. 14,807 of George D. ONeill.

When cathode 22, dynode l6 and positive grid I4 are connected to difierent potential points of more or less critical values in a direct-current power supply such that dynode I6 is lower in potential than grid [4 but positive in relation to the cathode, and dynode l6 and positive grid I4 are connected to resonator l8, oscillations will be generated in the triode as more fully described in the above-cited application Serial No. 681,454 of George D. ONeill. Energy from the dynode oscillator can then be abstracted at load couplin 20.

A high-frequency circuit formed by dynode rod 28 and the walls of resonator [8 as extended by terminal 34 and threaded ring 32 is divided ad- 4 jacent terminal 34 by direct-current insulating material without serious effect on that high-frequency circuit. The glass wall of the evacuated envelope enters the high-frequency field of the resonator without serious adverse eifect, and is well supported on the metal envelope wall that serves also as a shielding enclosure for the dynatron cathode structure, as a firm mechanical seat for the triode in the circuit assembly and as one wall of the bypass.

Detailedvariations of the foregoing novel features as well as applications of the features separately in other combinations will occur to those skilled in the art, wherefore I desire the appended claim to be accorded broad interpretation consistent with the spirit and scope of the invention.

What is claimed is:

High frequency apparatus having an electron discharge tube including a pair of mutually insulated electrodes and a generally conical metallic envelope portion extending from one of said electrodes and substantially enclosing the other of said pair of electrodes, a resonator coupled to said one electrode, said resonator having a generally conical seat receiving said metallic envelope portion and being spaced therefrom by a cushioning layer of dielectric material, and means firmly retaining said metallic envelope portion and said seat in assembled relation.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1 2,128,234 Dallenbach Aug. 30-, 1938 2,353,742 McArthur July 18, 1944 2,416,303 Parker Feb. 25, 194'? 2,419,800 Tomlin Apr. 29, 1947 2,429,811 Guarrera Oct. 28, 1947 2,432,193 Gubin Dec. 9, 19 47 

